There is a radio relay system via a relay station (RS) apparatus (see, for example, IEEE 802.16j). Received electric powers of a base station (ES) apparatus and mobile station (MS) apparatus improves because the base station apparatus and mobile station apparatus receive signal via the relay station apparatus. And, the base station apparatus can extend a transmission range of radio wave, and it can be attempted to improve location efficiency.
There are two kinds, A&F (Amplify and Forward) method and D&F (Decode and Forward) method, with respect to radio relay technology of the relay station apparatus and so on (see, for example, IEEE 802.16j).
In the A&F method, power amplification of reception signal and similar are performed without demodulation, decoding, re-encoding, re-modulation and so on, and received signal is transmitted, so that it can shorten a processing delay and suppress a relay delay. However, in the A&F method, noise and interference prior to relay are amplified and transmitted with the reception signal, so that a reception quality (for example, SINR (Signal to Interference and Noise Ratio)) deteriorates at a relay point.
On the other hand, the D&F method is a relay technology that the reception signal is decoded, error corrected, re-encoded, and transmitted. In the D&F method, error correction is performed, so that it can reduce the noise and interference prior to relay. However, in the D&F method, the processing of decoding, encoding, and so on are performed, so that the processing delay is bigger than the A&F method.
Furthermore, in the prior radio relay technology, it is discussed to control whether it performs frame encode processing after it performed frame decode processing for the reception signal, based on a manual operation, error rate, reception electric field strength, error bit number, or data type and the reception signal is transmitted, or it performs the fame encode processing without performing the frame decode processing and the reception signal is transmitted (see, for example, Japanese Laid-open Patent Publication No. 2001-156692).
However, in the prior art, the relay station performs the frame encode processing without performing the frame decode processing, so that the mobile station performs decode processing for two times, and a processing of the mobile station becomes complicated.